unit-testing - golang 中用于测试的模拟函数

Question

我想通过模拟其他包(package2)中的 FetchAllData() 和 SaveData() 为 CreateData() 函数编写单元测试用例，请帮助我用示例模拟该函数，

提前致谢

func CreateData(input package1.InputRequest) (output package1.OututResponse){

    ..some code
    ..some code

    DBdata, err := package2.FetchAllData() //function to fetch data from database

    ..some code
    ..some code

    id, insertErr := package2.SaveData(someData) //function to insert data

    ..some code
    ..some code
}

我只需要模拟上面的函数而不修改函数。我正在寻找那个

Answer 1

利用界面功能。它可能需要对依赖项进行一些更改(在本例中为 package2)。

将您的代码更改为类似这样的内容(重点是定义多个接口(interface)以提高可测试性):

type Fetcher interface {
    FetchAllData() ([]Data, error)
}

type Saver interface {
    SaveData([]Data) (int, error)
}


func CreateData(input package1.InputRequest) (output package1.OututResponse){

    ..some code
    ..some code

    // when you are writing tests, replace it with `s := NewMocking()`
    s := package2.NewStorage()

    DBdata, err := s.FetchAllData() //function to fetch data from database

    ..some code
    ..some code

    id, insertErr := s.SaveData(someData) //function to insert data

    ..some code
    ..some code
}

需要对 package2 做一点改动:

type MyStorage struct {}

func (s *MyStorage) FetchAllData ([]Data, error) {
    // ... some fetching code
}

func (s *MyStorage) SaveData(someData []Data) (int, error) {
    // ... some saving code
}

func NewStorage() *MyStorage {
    // ... some initialization
}

当你想做一些不需要package2的测试时，定义你自己的模拟类型:

type Mocking struct {}

func (s *Mocking) FetchAllData ([]Data, error) {
    // ... some mocking logic
}

func (s *Mocking) SaveData(someData []Data) (int, error) {
    // ... some mocking logic
}

func NewMocking() *Mocking {
    // ... initialize ...
}